As a technique that the present inventors have studied, a burn-in technique of the semiconductor device is considered as follows. That is, for example, the burn-in technique of a MCP forming a SRAM and a flash memory has the steps of forming respective semiconductor chips of the SRAM and the flash memory to a substrate, connecting electrically the semiconductor chips and the substrate by a wire bonding or the like, molding the semiconductor chips and the substrate with a resin to assemble a packaging structure, and then testing the packaging structure, wherein a temperature and an electrical stress which exceed a rating are applied to perform the burn-in technique. Because this burn-in performs a screening to eliminate some MCPs that may become bad (i.e., defective) in the future, only good MCPs are shipped as products.